2 * kallsyms.c: in-kernel printing of symbolic oopses and stack traces.
4 * Rewritten and vastly simplified by Rusty Russell for in-kernel
6 * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
10 * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
11 * Changed the compression method from stem compression to "table lookup"
12 * compression (see scripts/kallsyms.c for a more complete description)
14 #include <linux/kallsyms.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/seq_file.h>
19 #include <linux/err.h>
20 #include <linux/proc_fs.h>
21 #include <linux/sched.h> /* for cond_resched */
23 #include <linux/ctype.h>
25 #include <asm/sections.h>
27 #ifdef CONFIG_KALLSYMS_ALL
34 * These will be re-linked against their real values
35 * during the second link stage.
37 extern const unsigned long kallsyms_addresses[] __attribute__((weak));
38 extern const u8 kallsyms_names[] __attribute__((weak));
41 * Tell the compiler that the count isn't in the small data section if the arch
44 extern const unsigned long kallsyms_num_syms
45 __attribute__((weak, section(".rodata")));
47 extern const u8 kallsyms_token_table[] __attribute__((weak));
48 extern const u16 kallsyms_token_index[] __attribute__((weak));
50 extern const unsigned long kallsyms_markers[] __attribute__((weak));
52 static inline int is_kernel_inittext(unsigned long addr)
54 if (addr >= (unsigned long)_sinittext
55 && addr <= (unsigned long)_einittext)
60 static inline int is_kernel_text(unsigned long addr)
62 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_etext)
64 return in_gate_area_no_task(addr);
67 static inline int is_kernel(unsigned long addr)
69 if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
71 return in_gate_area_no_task(addr);
74 static int is_ksym_addr(unsigned long addr)
77 return is_kernel(addr);
79 return is_kernel_text(addr) || is_kernel_inittext(addr);
83 * Expand a compressed symbol data into the resulting uncompressed string,
84 * given the offset to where the symbol is in the compressed stream.
86 static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
88 int len, skipped_first = 0;
89 const u8 *tptr, *data;
91 /* Get the compressed symbol length from the first symbol byte. */
92 data = &kallsyms_names[off];
97 * Update the offset to return the offset for the next symbol on
98 * the compressed stream.
103 * For every byte on the compressed symbol data, copy the table
104 * entry for that byte.
107 tptr = &kallsyms_token_table[kallsyms_token_index[*data]];
123 /* Return to offset to the next symbol. */
128 * Get symbol type information. This is encoded as a single char at the
129 * beginning of the symbol name.
131 static char kallsyms_get_symbol_type(unsigned int off)
134 * Get just the first code, look it up in the token table,
135 * and return the first char from this token.
137 return kallsyms_token_table[kallsyms_token_index[kallsyms_names[off + 1]]];
142 * Find the offset on the compressed stream given and index in the
145 static unsigned int get_symbol_offset(unsigned long pos)
151 * Use the closest marker we have. We have markers every 256 positions,
152 * so that should be close enough.
154 name = &kallsyms_names[kallsyms_markers[pos >> 8]];
157 * Sequentially scan all the symbols up to the point we're searching
158 * for. Every symbol is stored in a [<len>][<len> bytes of data] format,
159 * so we just need to add the len to the current pointer for every
160 * symbol we wish to skip.
162 for (i = 0; i < (pos & 0xFF); i++)
163 name = name + (*name) + 1;
165 return name - kallsyms_names;
168 /* Lookup the address for this symbol. Returns 0 if not found. */
169 unsigned long kallsyms_lookup_name(const char *name)
171 char namebuf[KSYM_NAME_LEN];
175 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
176 off = kallsyms_expand_symbol(off, namebuf);
178 if (strcmp(namebuf, name) == 0)
179 return kallsyms_addresses[i];
181 return module_kallsyms_lookup_name(name);
184 int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
188 char namebuf[KSYM_NAME_LEN];
193 for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
194 off = kallsyms_expand_symbol(off, namebuf);
195 ret = fn(data, namebuf, NULL, kallsyms_addresses[i]);
199 return module_kallsyms_on_each_symbol(fn, data);
201 EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);
203 static unsigned long get_symbol_pos(unsigned long addr,
204 unsigned long *symbolsize,
205 unsigned long *offset)
207 unsigned long symbol_start = 0, symbol_end = 0;
208 unsigned long i, low, high, mid;
210 /* This kernel should never had been booted. */
211 BUG_ON(!kallsyms_addresses);
213 /* Do a binary search on the sorted kallsyms_addresses array. */
215 high = kallsyms_num_syms;
217 while (high - low > 1) {
218 mid = low + (high - low) / 2;
219 if (kallsyms_addresses[mid] <= addr)
226 * Search for the first aliased symbol. Aliased
227 * symbols are symbols with the same address.
229 while (low && kallsyms_addresses[low-1] == kallsyms_addresses[low])
232 symbol_start = kallsyms_addresses[low];
234 /* Search for next non-aliased symbol. */
235 for (i = low + 1; i < kallsyms_num_syms; i++) {
236 if (kallsyms_addresses[i] > symbol_start) {
237 symbol_end = kallsyms_addresses[i];
242 /* If we found no next symbol, we use the end of the section. */
244 if (is_kernel_inittext(addr))
245 symbol_end = (unsigned long)_einittext;
247 symbol_end = (unsigned long)_end;
249 symbol_end = (unsigned long)_etext;
253 *symbolsize = symbol_end - symbol_start;
255 *offset = addr - symbol_start;
261 * Lookup an address but don't bother to find any names.
263 int kallsyms_lookup_size_offset(unsigned long addr, unsigned long *symbolsize,
264 unsigned long *offset)
266 char namebuf[KSYM_NAME_LEN];
267 if (is_ksym_addr(addr))
268 return !!get_symbol_pos(addr, symbolsize, offset);
270 return !!module_address_lookup(addr, symbolsize, offset, NULL, namebuf);
275 * - modname is set to NULL if it's in the kernel.
276 * - We guarantee that the returned name is valid until we reschedule even if.
277 * It resides in a module.
278 * - We also guarantee that modname will be valid until rescheduled.
280 const char *kallsyms_lookup(unsigned long addr,
281 unsigned long *symbolsize,
282 unsigned long *offset,
283 char **modname, char *namebuf)
285 namebuf[KSYM_NAME_LEN - 1] = 0;
288 if (is_ksym_addr(addr)) {
291 pos = get_symbol_pos(addr, symbolsize, offset);
293 kallsyms_expand_symbol(get_symbol_offset(pos), namebuf);
299 /* See if it's in a module. */
300 return module_address_lookup(addr, symbolsize, offset, modname,
304 int lookup_symbol_name(unsigned long addr, char *symname)
307 symname[KSYM_NAME_LEN - 1] = '\0';
309 if (is_ksym_addr(addr)) {
312 pos = get_symbol_pos(addr, NULL, NULL);
314 kallsyms_expand_symbol(get_symbol_offset(pos), symname);
317 /* See if it's in a module. */
318 return lookup_module_symbol_name(addr, symname);
321 int lookup_symbol_attrs(unsigned long addr, unsigned long *size,
322 unsigned long *offset, char *modname, char *name)
325 name[KSYM_NAME_LEN - 1] = '\0';
327 if (is_ksym_addr(addr)) {
330 pos = get_symbol_pos(addr, size, offset);
332 kallsyms_expand_symbol(get_symbol_offset(pos), name);
336 /* See if it's in a module. */
337 return lookup_module_symbol_attrs(addr, size, offset, modname, name);
340 /* Look up a kernel symbol and return it in a text buffer. */
341 int sprint_symbol(char *buffer, unsigned long address)
345 unsigned long offset, size;
348 name = kallsyms_lookup(address, &size, &offset, &modname, buffer);
350 return sprintf(buffer, "0x%lx", address);
353 strcpy(buffer, name);
354 len = strlen(buffer);
358 len += sprintf(buffer, "+%#lx/%#lx [%s]",
359 offset, size, modname);
361 len += sprintf(buffer, "+%#lx/%#lx", offset, size);
365 EXPORT_SYMBOL_GPL(sprint_symbol);
367 /* Look up a kernel symbol and print it to the kernel messages. */
368 void __print_symbol(const char *fmt, unsigned long address)
370 char buffer[KSYM_SYMBOL_LEN];
372 sprint_symbol(buffer, address);
376 EXPORT_SYMBOL(__print_symbol);
378 /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */
379 struct kallsym_iter {
382 unsigned int nameoff; /* If iterating in core kernel symbols. */
384 char name[KSYM_NAME_LEN];
385 char module_name[MODULE_NAME_LEN];
389 static int get_ksymbol_mod(struct kallsym_iter *iter)
391 if (module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value,
392 &iter->type, iter->name, iter->module_name,
393 &iter->exported) < 0)
398 /* Returns space to next name. */
399 static unsigned long get_ksymbol_core(struct kallsym_iter *iter)
401 unsigned off = iter->nameoff;
403 iter->module_name[0] = '\0';
404 iter->value = kallsyms_addresses[iter->pos];
406 iter->type = kallsyms_get_symbol_type(off);
408 off = kallsyms_expand_symbol(off, iter->name);
410 return off - iter->nameoff;
413 static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
415 iter->name[0] = '\0';
416 iter->nameoff = get_symbol_offset(new_pos);
420 /* Returns false if pos at or past end of file. */
421 static int update_iter(struct kallsym_iter *iter, loff_t pos)
423 /* Module symbols can be accessed randomly. */
424 if (pos >= kallsyms_num_syms) {
426 return get_ksymbol_mod(iter);
429 /* If we're not on the desired position, reset to new position. */
430 if (pos != iter->pos)
431 reset_iter(iter, pos);
433 iter->nameoff += get_ksymbol_core(iter);
439 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
443 if (!update_iter(m->private, *pos))
448 static void *s_start(struct seq_file *m, loff_t *pos)
450 if (!update_iter(m->private, *pos))
455 static void s_stop(struct seq_file *m, void *p)
459 static int s_show(struct seq_file *m, void *p)
461 struct kallsym_iter *iter = m->private;
463 /* Some debugging symbols have no name. Ignore them. */
467 if (iter->module_name[0]) {
471 * Label it "global" if it is exported,
472 * "local" if not exported.
474 type = iter->exported ? toupper(iter->type) :
476 seq_printf(m, "%0*lx %c %s\t[%s]\n",
477 (int)(2 * sizeof(void *)),
478 iter->value, type, iter->name, iter->module_name);
480 seq_printf(m, "%0*lx %c %s\n",
481 (int)(2 * sizeof(void *)),
482 iter->value, iter->type, iter->name);
486 static const struct seq_operations kallsyms_op = {
493 static int kallsyms_open(struct inode *inode, struct file *file)
496 * We keep iterator in m->private, since normal case is to
497 * s_start from where we left off, so we avoid doing
498 * using get_symbol_offset for every symbol.
500 struct kallsym_iter *iter;
503 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
508 ret = seq_open(file, &kallsyms_op);
510 ((struct seq_file *)file->private_data)->private = iter;
516 static const struct file_operations kallsyms_operations = {
517 .open = kallsyms_open,
520 .release = seq_release_private,
523 static int __init kallsyms_init(void)
525 proc_create("kallsyms", 0444, NULL, &kallsyms_operations);
528 device_initcall(kallsyms_init);